It is possible one might become evident in the next few
months, even on Monday, when the US Department of Agriculture releases its
monthly Wasde crop report, a key event of the agricultural commodity traders'
diary.

While March Wasdes are usually among the lower profile
editions, this one could be among the few to reveal negative soybeans, as USDA
analysts battle with the challenge of matching large consumption of US soybeans
with, apparently, not-so-substantial supplies.

'Above-average
margins'

Demand for soybeans continues pretty much unabated.

Forecasts for 2013-14 soybeans in Wasde report, (existing figure)

US ending stocks: 141m bushels, (150m bushels)

Range of estimates: 130m-150m bushels

World ending stocks: 71.46m tonnes, (73.01m tonnes)

Range of estimates: 69.50m-72.90m tonnes

On the home front, processing remains strong. Latest
figures, for January, show the US soybean crush at 156.9m bushels, well above the
10-year mean for the month of 147.4m bushels,

"Don't overlook processing margins for soybeans and corn
ethanol which remain well above average levels," Richard Feltes, at RJ O'Brien,
said, even if there is some suspicion that the impact of porcine epidemic
diahorrea virus (PEDv) on the hog herd might begin to tell on feed demand.

And on exports, well, half way through the 2013-14 season
and the US is already overdrawn.

It has sold, or already shipped, 44.17m tonnes of the oilseed,
7.5% more than the USDA forecasts for the whole of 2013-14.

Different for corn

That might not matter so much if there were plenty of
soybeans to be found.

The USDA faces a similar picture in corn, where the US has
committed to 93% of exports forecast for 2013-14, a record proportion for the
time of year.

But as Don Roose, president of Iowa-based broker US
Commodities, said "there are still adequate supplies of corn around," which can
soak up an increase to the forecast for US exports which many expect in Monday's
Wasde.

For soybeans, the picture is not so simple, given that even
under current estimates, the US already looks like it will be running on
vapours at the end of the season, in August.

Pipeline minimum

The 150m bushels the USDA has pencilled in for domestic soybean
inventories for the end of 2013-14 may sound a lot.

Forecasts for 2013-14 corn in Wasde report, (existing figure)

US ending stocks: 1.488bn bushels, (1.481bn bushels)

Range of estimates: 1.431bn-1.656bn bushels

World ending stocks: 156.27m tonnes, (157.30m tonnes)

Range of estimates: 154.80m-158.40m tonnes

But there are always soybeans around on barges, boats, in
consumers' inventories which represent a floor, a so-called "pipeline minimum",
which it looks like the USDA believes to be 150m bushels this time, but which
are unavailable to the broader market.

"Last year, the USDA did not lower its stocks forecast from
February to August from 125m bushels," then considered the pipeline minimum, "and
many believe we are in the same situation this year," Rich Nelson chief
strategist at Chicago-based broker Allendale said.

So if the stocks figure is not reduced, how will the USDA
balance the books?

'Bloated with
soybeans'

One way is to stick by its existing forecasts, and there
could be cause to believe that the US will sell fewer soybeans than it has committed
to, if Chinese buyers ditch purchases and switch to South American supplies as
they often do at this time of year.

"The balance sheet is fiercely tight in soybeans, until we
see China starting to cancel orders," Mr Roose said.

And that could be around the corner.

"China is now bloated with soybeans. Soymeal basis levels in
China are in retreat and ships are backed up to unload soybeans," he said.

At Allendale, Rich Nelson said the USDA "may not be so aggressive"
in raising its forecast for soybean exports.

Besides, there is always the potential for considering that some
2013-14 exports can be met from early production from the 2014-15 harvest.

The residual number

But if USDA officials want to raise their soybean export forecast
and keep the stocks, the same they could do so through the, rare, use of a kind
of oilseed antimatter, a negative figure for the "residual" column, a rather
amorphous element which represents something of a relief valve on the balance
sheet.

Forecasts for 2013-14 wheat in Wasde report, (existing figure)

US ending stocks: 570m bushels, (558m bushels)

Range of estimates: 549m-615m bushels

World ending stocks: 183.65m tonnes, (183.73m tonnes)

Range of estimates: 182.10m-185.0m tonnes

The USDA has done so before, most recently in July 2008,
when the residual figure for the 2007-08 soybean balance sheet was cut to minus
35m bushels.

"Supply estimates and reported use through May, coupled with
the USDA's June 1 stocks estimate, indicate a below-average residual," the
department said at the time.

Crop underestimated?

At AgResource, chief economist Bill Tierney, told
Agrimoney.com that "what the USDA is saying is that we think the production
estimate will be changed down the line to give us more soybeans".

The USDA often changes soybean production estimates in
September Wasde reports, the year after harvest.

"Last year, they
raised the estimate by 19m bushels, the year before, for 2012, they raised it
by 38m bushels," said Mr Tierney, a former principal grains economist at the
USDA.

And the rises can be quite large, with the 2007 crop
upgraded by 91m bushels in September 2008, equivalent to 3.5% of production.

"This year, 3.5% would be equivalent to 115m bushels. That
could be enough to take ending stocks well over 200m bushels."

South America setbacks

Not that a negative residual is the only factor on investors'
minds heading towards Monday.

Forecasts for Wasde South American harvest estimates (existing figure)

Argentine corn: 23.35m tonnes, (24.0m tonnes)

Range of estimates: 20.8m-24.0m tonnes

Argentine soybeans: 53.50m tonnes, (54.0m tonnes)

Range of estimates: 52.7m-54.0m tonnes

Brazilian corn: 69.03m tonnes, (70.0m tonnes)

Range of estimates: 65.45m-70.5m tonnes

Brazilian soybeans: 88.14m tonnes, (90.0m tonnes)

Range of estimates: 86.5m-90.0m tonnes

There are South American harvests to consider, and the
potential for downgrades here, given excessive rains, after damaging dryness,
in Argentina, and bipolar weather in Brazil too, where western growing areas
are soaking, while eastern and southern farms are parched.

"I don't think the market is thinking that there will not be
a record South American harvest this year, it just won't be quite as big as had
been hoped," Mr Tierney said.

Mr Nelson said: "You might see 1m-2m tonnes taken off the
Brazilian soybean crop, but that probably would not affect the market too much."

Premature, or not?

And then there is the Crimea crisis to consider, and whether
the USDA will recognise a boost to US crop exports from concerns over Ukraine's
reliability as a shipper, with Russian troops deployed in its south.

"Ukraine's deliveries have not been a problem yet," Mr Roose
said, adding that the USDA is "not usually so premature" in making adjustments
to balance sheets so soon into an event is difficult to predict.

However, Mr Nelson said that with US export sales strong even
last week, before Russian troops entered Crimea, "it looks like even during the
early part of the Ukraine, the US was getting more sales from foreign buyers worried
about buying from Ukraine".

"We may find that, because of the Ukraine situation, the
USDA is a bit more aggressive" when it comes to lifting its forecast for US
corn exports.

Corn contortions

Not that any such upgrade would leave the US at risk of
reporting negative corn.

That is not just because of the ready supplies left over
from last year's record harvest, but is a matter of methodology too.

For soybeans, with exports and crush numbers closely
monitored, "the balance sheet is known. It forces USDA analysts to do it," in
resorting to a negative residual figure, Mr Tierney said.

For corn, "there is the huge feed and residual use element
which is not measured", meaning any discrepancies get swallowed up there.

Of course, this leads to its own difficulties, in interpreting,
for instance, the level of inventories the USDA reports for main crops every
quarter.